Quote from Konrad;1296195:
Probably the same as with pets - keep them summoned when you exp grind yourself. Martial Arts tournament or Saga ep 4 should work.
Quote from callback;1296198:
Saga ep 4 nowadays? With stuck mobs being patched? I know back when stuck was a thing I would summon a pet there to leech me, but it seems that without the bug it's too hard to efficiently farm it, and if you have the reforges to do so you'd be better IS bombing shyllien sasquatches to wipe the map.
Saga - yes, MA - no. You're right on the mobs being patched, but there is a trick you can do where you can lure one wyvern away from the crowd and keep it there so no one attacks it and it doesn't aggro anyone either, then you can attack anything else as freely as you want. Some people abused catchapon this way through Saga again.
MA on the other hand, while it's a good exp, it actually isn't very good monster exp, so it's not good for leveling pets.
The best way to level up your pet/partner is to do Shadow Wizard hm/elite, preferably during the 2x monster exp days.